Yup. Someone who was fighting for his life wouldn't be on top of the guy beating him to death. Good, law-abiding people stop when the threat is stopped. If they don't, regardless of what they were when the fight started, they have now become the aggressor and fair game for someone to employ deadly force to stop it.I think the key distinction in this story is 'beat to death'; and beat to death after saying 'I feel like killing someone'. At what point is this okay for an undercover anything to do?
His statement also rules out any of those other hypothetical circumstances some have been throwing out like chaff and flares.